let(:from_number) {Settings.mobile_http_api.sms_sender.from}

it "sends wakeup SMS from group 1 to users with last activity yesterday", :focus => true do
  MobileHttpApi::SmsSender.should_receive(:send_sms).with(:from => from_number, :to => user_2.msisdn, :text => wakeup_texts[:group_1][1])
  WakeupSmsSender.send
end

выдает ошибку 
     NoMethodError:
       undefined method `send_sms' for MobileHttpApi::Base:Class
